Is "Invite Your Friends" logic against Google Play Policy?

I'm thinking of implementing "invite your friends" popup in my game. It will be shown once in the game. If they invite their friends and their friends reach a specific level, the player who invited will receive some gifts in the game. There will be an invitation limit as well.

I'm using a registration system in my game, so it will be easy to implement this logic for me; but I was wondering if this is against Google Play Policy? I couldn't find anything related to this subject.